Incandescent lamp



ZECAN m Envision Application fiicd fi fl'ly 17, Boris! 33o. l ititlei.

This hit cation iclatcs to ii 51131528506111; clQQ- become so 'illOlOllfZlllf] cmiesilecl att c? o, slioz't vtrio lamps and in iti: olwjoct tlic proviuse as to sag; by tlioii" own weight or to locsion of a new anfi improvccl filamentary mmcome seriously sti'etclicol as 2-. terial posscssing special phyaical and clccrcsult of mechanical sliocl tricol properties. @t me allic filamcntotp" l have cliscovcrcd that tantalum is able to materials tungsten is the only sulistz. .cc assimilate 2a subct-antial ptopoztiom metal which has heretofore reccivetl extended comlic tungstcii the production an alloy ineicial use mfl this clcspitc certain practical having odizmtogeous physical and GlECiE'lLSl disadvantages, cliieif among which are a dcproperties for tli purposo in VlGW. For two N cidcd tcndcncy towaics c 'ystollizotion ac as a drawn wire I pie-for alloy containing companied by is known o1? Sll" about 90% of tzmtalmn anal 16% ct ting, namely a iisplacement of the crystals stcn, although Ldmntagcous results relative to each other resu' lting in wealzcning cuictl by tlzc use of o. considerably sznallci' or breakage of the metallic strand; and a, propoztion of tllflflfil'il'i or by a larger 15 rather low specific resistance, although the portion to the limit of What can be drawn latter is couplcd with a rather high temperainto wire comcnicntly in the ptopoltion ture cociiicicnt which holds tlie current (2011- of tungsten be gi'critcr than about 520%. sumption a proper point during actual At percentages above those which can be use, but-results in an ovcrsti'ong rush of cum rcilticcd to timmcntform by drawing in dies 29 rent instant a 12mm is turned on. which i is possible to work the alloy by rolling frequently protluccs miptiire ol' the filament ino strips "(132 i shearing into ribbons. The at this instant. It is very dillicult to readd ion of tungsten within tlzc limits licrcducetungsten to the form of a ductile wire in QSQt'ibQLl serves to enhance the electrical (sec Coolidge lPatcnt No. 1,582,933, issued z'esi taiicc dccreasc the resistance tempera- 25 December 30, 1913), apparently his difarc coetl'icicnt, tlccres se the tendency to cmficulty becomes so cnlm'ncctl lay the inclusion l ment by chemical rcactioowith 1'8 of even small proportions of other elements ."ioual and atloril greater rigidity dim m as to render it difficult if not impossible to alter heating Appoi'cntly the melt icmcfly these difficulties by the addition of 1119; point oftlio alloy is slightly greater, or other metallic inggi'eclients insmallquantitics. at least not less than, that of pure tantalum. Tantalum has iilso been suggested {1nd pnt- The light produced is of very satisfactory Qnlktl (sec Von Bolton Patient E o. 81173-2, CGlUX and the filaments exhibitno objectionissued April it), 1906) a filamentary matcaolc tendency to-Wart s crystallization or oil- '1'ial. and exhibits cci'tain features decidedly setting. The moi iimm'i ciecttical'i'csistancc 35 upcrior to tongstcn, notably a specific clecproduced wlici tlic ill fi n'lfi' lllfi ill'fi present tric resistance double that of tungsten at it; proportion which to;- come pun room tempcraturcs combi'oezl with o tcmposcs 1stl1cmostcicsirablc compaction. pcrature coefficient only two-thirds that of 15 well known that tl lfl spccit ccl ctric tungsten. Accordingly tlic Working" tcmrcsistzzmco of tungsten wncn cold is fryinperatuyc a tantalum filaincnt will be sub PQTEUYQIYJOWI lit-mg less than that 01' tin stantially larger than a tungsten filo ient of platinum, iron, nickel, and cvcn than brass the same length and capacity, which affords v liicli i5 supposed to iie a metal of CGIHPELKS: increased light cn'iitting surface combined tlvclyhigliconcluctivity. On the otlicz'non zl with a ggnallggytendgngv to "lraw an unduly the rcsistancc, temperature cocflicicnt 28 meat initial current. ll ontzilum, however, rather lllgll \llli1ll tv.-o propci'ticslaltcn tolms cxliiliitc l certain practical ilcfecls, 'nogctlici' I'cquno lamp tiiai icnts n mlc from I llllllVI :1 tcmlencv to riisiiitcggrntiozi umlcitlio pun tungstcn lo liftflf ll llllilflfii fiilylfi1',fI("'l" SS inlii lcncc of alto coating :1 tendency, FOchon to carry inc nclccsmi'y cmuf'cizt under in the [)TUSLIK'G of am iilmzl nili'ogcn to opcrzitingrcomlitmnooml lure entails l lac film 59 bccome brittle with ilS ccizilly at the nwnl of oucli low r-csixtzmcc wlzcn colcl tlmt ll prod ucetl.

comparativelv cool plzu more the filament dccidml over rush of current i is attached to tho loading-iii wires; and a1 Alloying will: to itclum int-mos n tenfincy for the otmng'ly lam ,o portions to Eltlcll'ic resistance when colo and UL sistance temperature coellicient less even than amounts and produce the temperature coefiicient thereby overcomingthis tendency.

On the other hand tantalum alone ollers the disadvantages of being unduly soft and jarred. out of shape by shocks. B3 alloying the two metals together it is. possible to produce an incandescing body having a meltpoint at least about 52800 centigradc and a specific electrical resistance more than twice that of tungsten conibinedn'ith a rethat of tantalunn I am not aware of any other combination of metals which ill produce this result, although there are at least two alloysol tungsten and tantalum which will (lo-this, namely those having a preponderance of tungsten and those having preponderance of tantalum and I desire to claim and secure both compositions although I preferably employ that composition lmn ing a preponderance of tantalum and have directed my specific claims to this end.

I do not exclude the use of minor propow .lions of other ingredients designed for the purpose of facilitating radiation or emission of. light waves, electrons, etc., such thorium, zirconium.

or such non-n'ietallic additions as rnre-earths themselves or the alkaline earth. oxides which, if used at all, occur only in small.

only their own particular etlect.

and other rare-earth metals,

Having, thus described my invention what 1 claim is:'

.1. An inrmulescing body for electric lamps cons imp; oi: lll alloy containing from to 99% metiulic tantalum and 1% to 50% of metallic tungsten combinedtogether in the form of a homogeneous alloy.

2. An incandcscingbody for electric lamps wrought strand of a binary alloy of tantaliuu and tungsten wherein the tantalum constitutes at least about 50% of the whole and the tungsten at least about 105,.

53. .in lHFIHHlOH'lHg bod for electric lamps consisting of a solid solution alloy containing at least about of tantalum and a! least about 1%, of metallic tungsten.

consisting of a l. Au incandcscing body for electric lamps consisting of a drawn wire of an alloy containing tantalum. and tungsten wherein the tantalum comprises about of the whole.

5. A mciallic incandcscing body for electric lamps consisting of an alloy containing essentially tantalum and tungsten having a melting point at leastabout2800 Centigrade and a specific electrical resistance when cold morethan twice that ot tungsten combined with a. resistance temperature coefiicient less than that of tantalum.

1n testimony whereof I osoAn v Mariana.

hereunto ailix my signature (ill 

